Thermoplastic Urethane Structure and Ultraviolet Stability

Schollenberger, C. S.; Stewart, F.D.

doi:10.1177/009524437200400404

Cited by 46 publications

(31 citation statements)

References 7 publications

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“…It is not known whether or not both urethane and urea linkages are attacked or whether the urea linkages are lost with the rest of the cross-linker, though the results with the styrene-containing acrylic copolymer would suggest that attack is primarily at the urethane site. Loss of urethane cross-links has been observed during photolysis of polyols cross-linked with aromatic isocyanates (Wagner and Mennicken, 1962;Beachell and Chang, 1972;Matusak et al, 1973;Schollenberger andStewart, 1973, 1976;Schultze, 1973;Osawa et al, 1975;Allen and McKellar, 1976). The effectiveness of the hindered-amine light stabilizer in preventing the loss of urethane cross-links suggests that the loss might be due to free-radical attack on the urethane bond.…”

Section: Resultsmentioning

confidence: 99%

“…Although isocyanate cross-linking chemistry has been studied in great detail (Chadwick and Cleveland, 1981;Ozaki, 1972;Saunders and Frisch, 1962), there have been no reported studies of the kinetics of cross-linking and the implications to network formation in actual coating formulations. Studies of degradation in isocyanate cross-linked coatings have focused on hydrolytic stability of urethanes and ultraviolet (UV) induced oxidation of aromatic isocyanates (Wagner and Mennicken, 1962;Beachell and Chang, 1972;Matusak et al, 1973;Schollenberger andStewart, 1973, 1976;Schultze, 1973;Osawa et al, 1975;Allen and McKellar, 1976). Other workers (Baker, 1980;Boch and Uerdingen, 1980) have studied the effects of different polyols on the physical durability of urethane coatings.…”

Section: Introductionmentioning

confidence: 99%

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Cure and photodegradation of two-package acrylic/urethane coatings

Bauer¹,

Dickie²,

Koenig³

1986

Ind. Eng. Chem. Prod. Res. Dev.

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Ind. Eng. Chem. Prod. Res. Dev. 1986, 25, 289-296 289 of composites fabricated with resin-treated coir fiber mat showed an posites based on untreated coir fiber mat a significant reduction in ILSS was observed ( Figure 11).It may be concluded from these studies that a coating of USP resin on coir fibers improves the compatibility of Kulkarnl, A. G.; Cheriyan, K. A.; Satyanarayana, K. G.; Rohatgi, P. K. J. Appl. folym. Scl. 1983, 28, 625. Mukherjee, R. N.; Pal, S. K.; Sanyal, S. K.; Sanyal, S. K. J. Appl. po/ym. Scl. 1983, 28, 3029. Prasad, S. V.; Pavithran, C.; Rohatgl, P. K. J. Mater. Sci. 1983, 18, 1443. SrMhar, M. K.; BasawaraJappa, G.; Kasturl. S. G.; Balasubramanlum I n d h J. Texf. Res. 1982, 7 , 87. Varma, D. S.; Varma, M.; Varma, I. K. Text. Res. J. 1984, 54, 827. Varma, D. s.; Varma. M.; Varma, I. K.. "Coir Fibers I1 Evaluation as a reinforcement in unsaturated polyester resin", J . Reinf. flast. Compos. 1985. 4 . 419. at humidities, for 'Omfibers with matrix resin and improves the aging characteristics of composites. Varma, 'D. 'S.; Varma, M.; Varma, I. K., "Composite Materials from Coir Fibers", submitted for publication to folym. Mater. Scl. Eng , Registry No. Acrolite 404, 101374-98-5. L i t e r a t u r e Cited Belmares, H.; Barrera, A.; Castilio, E.; Verheugen, E. V.; Monjaras. M.; Patfoort, G. A.; Bucquoye, M. E. N. Ind. Eng. Chem. Prod. Res. Dev. 1981, 20, 555.The chemistry and kinetics of cure and hotodegradation of two-package acrylic/urethane coatings have been band in the infrared has been found to obey simple second-order kinetics. The activation energy of the cross-linking reaction is 8.2 kcal/mol. Second-order kinetics and the relatively low activation energy lead to coatings with greater cure latitude (substantially wider cure windows) than typical acrylic/melamine coatings of similar composition. The urethane cross-links formed on cure are found to degrade on exposure to ultraviolet light. Loss of urethane cross-links has been found to be photochemical rather than hydrolytic in nature. The chemistry of cross-link degradation is a function of the composition of the acrylic copolymer and can be greatly inhibited by the addition of hindered-amine light stabilizers. measured by infrared and magic-angle ' t: C NMR spectroscopies. The rate of disappearance of the Isocyanate

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Cure and photodegradation of two-package acrylic/urethane coatings

Bauer¹,

Dickie²,

Koenig³

1986

Ind. Eng. Chem. Prod. Res. Dev.

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“…This, of course, severely limits their use in situations which require even moderate exposure to sunlight. As a consequence, considerable attention has been given over the past two decades to the study of the photodegradation process of aromatic diisocyanate based polyurethanes (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14).…”

Section: Introductionmentioning

confidence: 99%

“…In pioneering investigations of the photodegradation of MDI and TDI based polyurethanes, Schollenberger and coworkers (4)(5)(6)(7) and Nevskii, Tarakanov, and coworkers (8)(9)(10)(11)(12) both postulated the formation of mono-and diquinone imide products (Scheme I).…”

Section: Introductionmentioning

confidence: 99%

Effect of crystallinity and flexibility on the photodegradation of polyurethanes

Hoyle

Kim

1987

J. Polym. Sci. A Polym. Chem.

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Using fluorescence spectroscopy and gel content measurement, the photolysis of simple polyurethanes based on methylene 4,4′‐diphenyldiisocyanate (MDI) is shown to depend on both the flexibility and crystallinity of the polymer. Polyurethane films based on MDI and 1,12‐dodecanediol (MDI‐12) can be either annealed or quenched to yield a semicrystalline (as measured by DSC and X‐ray diffraction) or amorphous film, respectively. In the case of the quenched (amorphous) film, photolysis yields an ortho photo‐Fries product whereas the annealed (semicrystalline) film does not. Similarly, for a given photolysis time the annealed film generates a lower extent of crosslinked gel. In addition, photolysis of amorphous polyurethane films derived from MDI and ethylene oxide oligomers shows that for relatively inflexible polymers with only three ethylene oxide segments, little or no ortho photo‐Fries rearrangement products are generated upon photolysis. In contrast, photolysis of more flexible polyurethane films with approximately 13 ethylene oxide linkages yields the ortho photo‐Fries product. Apparently, for aromatic diisocyanate based polyurethanes, the extent and mechanism of degradation is directly dependent on the crystallinity and main‐chain flexibility of the polymer.

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“…These behaviors have been studied rather extensively for rigid polyurethane foam (PUF), which is the matrix of FRU; for example, in papers [1] and [2] for thermal degradation, and papers [3], [4] and [5] for photo-degradation. Photo-degradation, in particular, has been an issue of critical concern in the practical application of many of the PUF moldings derived from aromatic polyisocyanates.…”

Section: Introduction Ow-expansion Polyurethane Foam Uniformly Reinfomentioning

confidence: 99%

Thermal and Photo-Degradation Behaviors of Glass-Fiber Reinforced Rigid Polyurethane Foam

Morimoto

Suzuki

Yosomiya

1983

Journal of Composite Materials

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Thermal and photo-degradation of rigid polyurethane foams (PUF) and glass fiber reinforced rigid polyurethane foams (FRU) have been studied.It was found that FRU and PUF showed the nearly the same degradation behavior for flexural properties. In general, slightly higher degradation was observed with samples of lower expansion ratio, higher apparent density and containing glass fiber of shorter length.Measurement of interlaminar shear strength of heat-treated samples suggested that reduction in this property would be ascribable to the reduction in both the shear modulus of matrix and the bonding strength between matrix and fiber. No significant difference was observed among the types of samples in the degradation behaviors for flexural properties after WOM exposure, but samples of higher apparent density tended to show a slightly higher degradation. IR analysis revealed that some of the urethane linkages contained have been lost after WOM exposure.

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Thermoplastic Urethane Structure and Ultraviolet Stability

Cited by 46 publications

References 7 publications

Cure and photodegradation of two-package acrylic/urethane coatings

Cure and photodegradation of two-package acrylic/urethane coatings

Effect of crystallinity and flexibility on the photodegradation of polyurethanes

Thermal and Photo-Degradation Behaviors of Glass-Fiber Reinforced Rigid Polyurethane Foam

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